20 ms·

Eighteen months of Django

104 points by dangoldin 13y ago

tesmar2 13y ago
As someone who is thinking about doing a python project, should I learn Django or just go with Flask? Any thoughts on those two?
- dangoldin 13y ago
  I think it really depends on what the project is. If it's relatively simple and you don't really want to deal with user registration/databases I'd say definitely go with Flask. Django does a pretty good job of those two but until it "clicks" you end up being confused.
  - aartur 13y ago
    Funny that I wrote that Flask is for advanced usage and you wrote that Flask is for simple usage. If the project is really simple - no database, no declarative forms etc. - then Flask will be better. But if you go to "medium complexity" Django gives you ready components which you need to integrate in Flask (SQLAlchemy, WTForms etc.). You also need to invent your own project structure, and Django already has a hardcoded one. When the project complexity is "high" then Django starts to be too limited/"hardcoded" and flexibility/minimalism of Flask starts to shine.
    - dangoldin 13y ago
      Haha yea you're right! Funny how my bias trickled through. I haven't done too much Flask customization and only use it for the one off simple project that just need a web interface. Django is definitely more in the range of "we want you to write" this way but I've found it to be at least a bit more customizable than RoR. Flask is on the other extreme which lets you do whatever you want.. but you're the one who has to do it.
    - numlocked 13y ago
      I actually disagree. Flask does not necessarily shine with projects of high complexity. The framework designers themselves say as much: "However Flask is just not designed for large applications or asynchronous servers. Flask wants to make it quick and easy to write a traditional web application."[1] Flask is excellent when you just don't need a bunch of the stuff in Django, and don't need the batteries to be included. It's not so much that Flask is suitable to high-complexity apps, but more that it's suited to highly custom web apps. Building a music sharing app based on jQuery mobile and backed by Mongo? You're better off with Flask. But at scale you're going to end up doing something custom. Django is highly suitable if you need to manage users, have a variety of entities that lend themselves to the admin dashboard (more broadly, that the admin/public app metaphor even makes sense in the first place), and find a plug-and-play package system compelling. They are both great frameworks, but "complexity" (advanced/simple) is the wrong axis along which to evaluate them. [1]http://flask.pocoo.org/docs/design/ http://flask.pocoo.org/docs/design/
      - dvanduzer 13y ago
        The "large applications or asynchronous servers" bit might be better understood in comparison to the monolithic versus micro kernel debate. Flask is well suited for building complex applications that can be decomposed into simple moving parts with a clear separation of concerns. (My personal bias is that all complex applications can and should be developed this way.) The documented limitation you reference is based on the WSGI server being used. "If your server uses some kind of concurrency that is not based on threads or greenlets, Flask will no longer be able to support these global proxies."[0] As nginx+gunicorn is becoming more popular, this isn't really an issue at all. [0]http://flask.pocoo.org/docs/becomingbig/#scale-like-a-pro http://flask.pocoo.org/docs/becomingbig/#scale-like-a-pro
      - espeed 13y ago
        "However Flask is just not designed for large applications or asynchronous servers. Flask wants to make it quick and easy to write a traditional web application." Armin has said before that he needs to update/clarify that statement -- as dvanduzer said, it's not really relevant anymore.
- ioddly 13y ago
  I suppose it depends on what your goals are. If your goal is just to crank out some Python, I'd go with Flask (or my personal favorite Bottle).
- aartur 13y ago
  If you are new to Python and just want to have a working project instead of tinkering, then Django is better suited. Flask is for more advanced uses where you need to have more control or be able to integrate components you choose (like SQLAlchemy instead of Django ORM, or a NoSQL DB).
  - mikeyouse 13y ago
    I disagree somewhat.. I'm a hobbyist at best when it comes to programming. Like I've never actually shipped anything in my life. I recently decided to put an end to that to solve a problem for a family member's business. They just wanted a simple web form, where the sales people could add notes throughout the day and then automatically email those notes to the owner at the end of the day. I first tried Django and was quickly overwhelmed.. I switched to Flask and with the help of flask-login, flask-wtforms, and flask-mail, it only took me a long weekend to get it up and running. Just a personal anecdote, but Flask was much easier for me.
    - obviouslygreen 13y ago
      Flask is definitely easier... it also offers far less. Which is fine in some circumstances -- perhaps many -- but the fact that Django has a steeper learning curve is due to the fact that it covers a lot more ground in terms of things many if not most web applications need. This doesn't make it better, but it also doesn't make it worse.
- hamax 13y ago
  I really like Flask but I still go with Django when I need the admin.
- aidos 13y ago
  Neither! Actually, as the others have said it completely depends on what you're making. Django is great if you're making a standard cms type website. News feed, blog, etc. There's a bit of a learning curve but it gives you a lot of the scaffolding out of the box (and there are loads of examples to learn from). It has the biggest community (I guess?) so you'll always be able to find answers / libraries / sample code. Use Flask if you really want to get a website up and running with half a dozen lines of code. You'll have to build everything else yourself; admin, authentication, etc etc - though there are good extensions for a lot of things too. Thinking about it - if you don't know either of them, spend a day with Flask, by the end of it you should have a fairly good idea of what you get with it. Then run through the Django tutorials. It'll take longer but you'll be impressed with how quickly you can get something fairly complete up and running. For me, I lean towards Flask (heavily). When you think about what Django does - it's basically a web container with a db/model layer and sensible scaffolding for the views (front and admin). I prefer to use SQLAlchemy (if I'm working with a relational db). In terms of the admin I think that the days of writing admin grid and edit screens that post back and forth to the server are numbered (I use REST and Angular now) - so that's not a bit of Django I use either. By the time you've ripped all that out you may as well save yourself all the config and just use Flask. Having said that - LEARN THEM BOTH. At least just a little bit so you can see for yourself where each one shines. These days I approach it completely differently. My last two projects have involved a fair amount of complex business logic (and processing work). I've written the libraries I needed first as standalone packages, only introducing Flask as a final step. The web wrapper is just there to provide a web interface (mostly an api) access the db layer and glue it all to my libraries. I'd recommend this approach as it stops you from thinking along the lines of "ok, I'll need to create 3 Django apps, here are my models for each, should I put this code in the models.py or the views.py?" Instead you concentrate on making the real python code to do the heavy lifting, and you architect that sensibly without having to worry about how the web framework would normally prescribe it to be done. You'll end up with far more portable code in the long run.
  - mailshanx 13y ago
    What is your opinion about web2py? I started exploring it a week back, and it seems to have a lot of built in functionality. I thought it would be the easiest web framework to get started with (since it was originally built to help teach students about web programming). However, it seems to have a vast number of components, and it looks like learning all of it would entail almost the same effort as learning Django...
- ConceitedCode 13y ago
  You might also want to take a look at Pyramid. There's pros and cons for each.
  - HarryRotha 13y ago
    I absolutely love pyramid, but I found the learning curve for it to be much higher than flask or django. If pyramid had a few more things working in a simple way out of the box I would go for it every time.
- greghinch 13y ago
  I've been building (more or less solo) a web app marketplace for our startup for about a year now. I love Python, and had dabbled in Django and Flask prior to this, but built nothing with either to any significant degree. I went with Django because I was able to get something up relatively quickly, and I feel like that was a solid decision. I also am relatively confident in my ability to move towards Flask in the longer term if the Django app becomes too much, but I haven't experienced that yet. Also Heroku has been mostly a godsend, as I haven't had to spend nearly any time on sysadmin stuff. One thing that caught me early on, not sure if it's a bug or what, but in Heroku, if you use git URLs for some of your packages in pip requirements (which is useful if you need to customize a package or more frequently fix a bug and can't wait for it to be pushed to pypi), Heroku's package cache has trouble knowing when to update unless you a) change the package version in its setup.py (may or may not be a good idea) or b) change the Python version in runtime.txt (kind of a pain as generally that means two deploys for an update, bump down one minor, then back up).
- obviouslygreen 13y ago
  Flask is so simple that it's definitely worth picking that up regardless (in any case, I think it's well done and worth having in your arsenal). However, for large web projects, Django beats it hands down. Doing similar work with Flask would require so much wheel-reinvention that it'd be hard to justify your time or your client's money when it's all built quite well already. Of course it's not perfect, and it's not for everything. But it's a great general-purpose, medium-performance web framework. It becomes a pain on very high-traffic sites (perhaps more so than JVM-based solutions and on par with scaling Ruby frameworks), but if you use it in the right place and/or team up with systems people that know their stuff, it's a powerful tool for quickly building complex websites in a maintainable and intuitive way.
  - porker 13y ago
    Good point, I'd not thought about the JVM based Ruby solutions which can be used. If they'd give more Scala-like performance.. IronPython?
jspiral 13y ago
nice summary, sent to a colleague who is starting with django.
- dangoldin 13y ago
  Glad to have helped. If he/she has any questions you can have them reach out to me. I'm definitely not an expert but can offer some suggestions. dangoldin gmail is the email.
adamrt 13y ago
Using S3 for static media makes perfect sense, but does anyone have information on S3 when your contributors (users in the admin) are uploading lots of images for via something like django-filebrowser or a simple zipfile upload (that extracts the images into a folder)? I haven't seen anything like this in any examples.
- stevenwei 13y ago
  I think the standard method of dealing with this is to have your users upload the items to the local web server and then have some sort of async task or cron job responsible for moving the files to S3 later on. Of course this means you'll have to keep track of where the uploaded file is currently located, but if you ever want to scale to multiple web servers you'll need to do that anyway.
  - dangoldin 13y ago
    Yea - this is how I've been doing it. The server that gets the upload does some processing and then moves the content over to S3 and adds an entry to the database that references it. It also forces you to write stateless code which is nice bonus.
- obviouslygreen 13y ago
  This is supported quite well via django-storages. Unless the libs you're using are doing something manual instead of using Django's built-in file handling, this will neatly override the local-filesystem defaults and send all of your content to S3. http://django-storages.readthedocs.org/en/latest/ http://django-storages.readthedocs.org/en/latest/
- adrianh 13y ago
  You can use S3's CORS support to allow your users to upload directly to S3 without even touching your server. Downside is that it can be hard to debug and it requires your users to use JavaScript -- but otherwise it's a big win. See http://philfreo.com/blog/how-to-allow-direct-file-uploads-from-javascript-to-amazon-s3-signed-by-python/ http://philfreo.com/blog/how-to-allow-direct-file-uploads-fr... for a Python example.
porter 13y ago
One more addition: Use heroku.
- boffo9 13y ago
  Heroku is the best!
- porter 13y ago
  Not sure why this got downvoted. I was being completely serious. Beat having to deal with fabric.
hiddentaco 13y ago
Great short and concise article. I'm in the process of writing a pet project using Django and would really appreciate your insights on what packages you find useful (as mentioned at the bottom of your post).
- deleted 13y ago
  [deleted]
- obviouslygreen 13y ago
  From someone who wasn't asked but has input... ;) It's not a Python package in the sense that you might mean, but using virtualenv is absolutely fundamental to good Python development (at least the kind that lets you keep your sanity). South is also exceptional; however, the developer recently ran a successful Kickstarter campaign dedicated to creating an improved version intended to be merged with Django itself, so that's something to watch for. Django-CMS has proven invaluable for many of my projects and clients, though it's very heavy and more of a project-tacked-on-to-your-project than just a package. It's great to know, though, and very powerful. django-registration can be useful if you're into full-on user profile usage, though many sites don't actually need this. There's a separate project that provides a set of default templates for this package, and it's almost more useful than django-registration itself. livesettings is an outgrowth of django-cms that's pretty useful when you need what would otherwise be settings.py constants that can be modified at runtime without a deployment and server restart. Be careful, though, as overuse of this means you might have design issues. feedparser is a very, very easy way to consume XML feeds. If you want to parse something in a very user-friendly way, BeautifulSoup is hard to beat. If you're into the nitty gritty and/or need serious performance, lxml serves the same purpose but kicks far more ass. If you need to interface with Amazon's AWS environments (EC2, S3, etc.), boto is a brilliant library. These are more Python-in-general than Django-specific, but that's often a good thing.
  - hiddentaco 13y ago
    Thanks for the reply. While all suggestion are useful the biggest take away for me is livesettings. TBH I can't think of how I would use it at the moment but I can see that it could come in handy later.
tomkinstinch 13y ago
I'll add that if you need to background anything, django-celery makes it easy. celeryd is also good for scheduling tasks with either single or periodic execution. http://docs.celeryproject.org/en/latest/getting-started/first-steps-with-celery.html#first-steps http://docs.celeryproject.org/en/latest/getting-started/firs... You can also use it in a typical task queue role. It will pickle or serialize the Python objects that accompany tasks for transmission over the wire.
- obviouslygreen 13y ago
  Note that periodic execution, one of the more useful aspects of celery, is not supported on all backends. If you're using rabbitMQ, you're golden. If you're using most or all other transports (including SQS), you're likely SOL and will have to resort to either bare cron jobs or something like django-cronograph that accomplishes the same thing. celery is definitely nice, but it does have its limitations (like everything else).
  - hiddentaco 13y ago
    I'm really interested in peoples opinion on Celery vs Others when using Django. I'm about to hit a point in my pet project where I need something but I havn't chosen my approach yet. I've ehard Pyres is better than Celery.
    - obviouslygreen 13y ago
      Once you wrap your head around one (embarrassingly, it took me a while to really understand what celery was doing -- I had an easier time getting comfortable with the multiprocessing library), it shouldn't be difficult to pick up another and compare them locally. Celery does what it's supposed to; that's about all I can say for it. I'd suggest writing a few simple jobs and testing them in similar environments under as much load as you can. Look for things like consistency of logging and running tasks exactly once across multiple consumers despite the semantics of the queue you pick.
  - crdoconnor 13y ago
bluepanda_ 13y ago
Interesting post. I decided to use Django for our startup because Python was a requirement, we're planning to have a lot of customers, and Django seems like the most appropriate choice for large scale apps. While I've mostly used non-rel databases, I'll be using postgresql as a database, because it seems to be highly compatible with Django, because Heroku makes scaling it easy, and because it's a good occasion to learn some RDBMS.
boffo9 13y ago
I'll add that you should read Two Scoops of Django at http://django.2scoops.org http://django.2scoops.org
porker 13y ago
How well does Django handle complex forms? The kind where "if x = y show fields p-r (and make them required), if x = z jump the next screen)? I've just implemented one of these in PHP using the 'old' Symfony 1.4 and it was painful. I ended up hardcoding most of the frontend, and writing ridiculous modifications for "add another row" and validation. Is Django any better at that? Complex forms have been my pain point for over 11 years, and if a framework handles them... I'm in!
- ShaunCodeweaver 13y ago
  Very much this - though I've experienced this in other stacks. Would love to know the best way people handle this.
- scott_w 13y ago
  If I'm understanding you correctly, you want to have the fields on the form depend on the contents of what was entered on the previous form e.g. if user selects name, ask for name, otherwise ask for address. In that case, I tend to use class-based views and set different forms, templates etc. depending on those values. If the form is different enough, it's easier just to send them to a completely different URL.
  - porker 13y ago
    Not quite - that happens sometimes and I use logic in the controller (ugh) to switch the form class. This is what I mean: an adaptive form http://screencast.com/t/SutggDU5 http://screencast.com/t/SutggDU5 The server-side validation has to adapt depending on the data coming from the client-side, and varies a lot. Perhaps others don't build forms like this much and so web frameworks don't deal with them; I get one like this every few months!
    - scott_w 13y ago
      Ah, I see now. For certain cases e.g. repeating the same form over and over, you can use formsets, but that doesn't work when you have two different forms. I still think a solution is to use multiple forms and form types rather than one big form. Perhaps you can prefix the field names on the template and use that to determine which form they go to inside the view. It makes your logic a little simpler in any case.
groundCode 13y ago
Nice post thanks - I'm about to tackle a fairly large Django project so it's always nice to see some best practice guidelines
scott_w 13y ago
For dealing with packages such as python-psycopg2 and python-mysql, your best bet is to use --system-site-packages. This allows the virtualenv to depend on packages provided by your distro instead of trying to compile its own. Wherever possible, I try to do this with Python packages that require a C compiler to make deployment a little easier and reduce dependencies. Personally, I'm not a fan of Fabric and I much prefer configuration management (Salt, Chef, Puppet) because of the added flexibility you get. About the most I use Fabric for is logging into the Salt Master and kicking off a deployment process.
- antihero 13y ago
  Absolutely not. An added bit of compile time is the least of your worries and if you really don't want to compile stuff on production, look at packaging your virtualenv as a compiled deb/rpm. Never ever ever mix/depend upon system packages in your virtualenv. Ever.
  - scott_w 13y ago
    You're always depending on system packages somewhere. Compiling isn't the only reason - sometimes it's necessary just to make the damn thing work. Some examples: * PIL - Using Pip's version on Ubuntu, you have to hack your directory structure and re-compile the whole thing or PIL doesn't compile in support for your image libraries. * psycopg2 - This is hit and miss (OS X comes to mind), but depending on the system version guarantees that it has been tested to work with the specific version of Postgres on your system. * Crypto libraries - Broken packages have ended up on Pip and just cause a bloody headache. The system package is, again, tested and works. Compiling a DEB/RPM would be a good idea, but it's not a well supported system at all. If there were a simple pip compile --type=deb or something, we would be all over it.
    - antihero 13y ago
      PIL - Don't use PIL, use Pillow. Psycopg2 - Well, it's just a client library - surely you will be making sure your client matches your server's version (whether that's local or a clust or whatever)? Sure your system will likely need Postgres headers installed, but why is that an issue? Actually, let me just check that. e: Yeah, you need libpq-dev installed, but I fail to see the point here? You need to make sure you have python-dev and a correct version of Python installed, too. PyCrypto - Hmm, not had a problem with this hugely. What I was suggesting doesn't involve a deb of individual packages, but a deb of the entire app/virtualenv.
jordn 13y ago
For those who would like to get started with Django, here's a skeleton project https://github.com/jordn/heroku-django-s3 https://github.com/jordn/heroku-django-s3 and guide helps get you set up quickly with: - hosting on heroku - static files on Amazon S3 - virtualenv(wrapper) isolated packages - environment and security critical variables removed from settings.py and stored as environment variables (following the 12-factor design ethic)
- iends 13y ago
  I have a couple of thoughts: 1. Why not use django-admin.py startproject --template=<url>? I typically do something like django-admin.py startproject --template=https://github.com/rdegges/django-skel/zipball/master https://github.com/rdegges/django-skel/zipball/master mynewproject so I don't actually have to clone 2. No runtime.txt for heroku? 3. Not specifying version numbers in your requirements.txt is very dangerous. I prefer something like "Django>=1.5.0,<=1.5.9"
  - jordn 13y ago
    Thanks! Basically the answer is that I wasn't aware of the possibility of those things and have tried to keep it as simple as possible. I made a skeleton project for me as I couldn't find a decent guide for deploying django static's on s3. I fumbled my way through it and corrected and formalised it later so I could do it again. The https://github.com/rdegges/django-skel https://github.com/rdegges/django-skel project looks really useful as it contains everything and more you might want to use for a django project (and more), though not yet knowing what magic's it's doing I wouldn't yet jump to use. 1. That is very neat. I hope to try and copy that. 2. Noted. I didn't realise the need, as python 2.7.4 is the default. Can see it causing headaches if this were to change however. 3. Why is it dangerous? I preferred to keep the version numbers so it would always just install latest versions without any extra effort.
    - iends 13y ago
      The reason it's dangerous is that packages can introduce backwards incompatible changes. If you have a project that you don't work on for a few weeks/months and then need to fix a bug, you're going to have to spend additional cycles tracking down the issue and fixing either the backwards incompatible change, or adding a specific version to your requirements file anyway. I like to try and scope the package versions at the level the maintainer promises not to introduce breakages at.
ludwigvan 13y ago
Here are a few other Django packages that I haven't seen mentioned in this thread: - Gargoyle: Feature switches in Django https://github.com/disqus/gargoyle https://github.com/disqus/gargoyle - webassets and django-assets: For minifying static assets - raven + sentry for logging. Sentry is the server, so actually can be used with any project, not only Django. - django_extensions: Provides some helper management commands, for example manage.py shell_plus which automatically imports your models - dbbackup for backing up your db to S3 or Dropbox

104 points by dangoldin 13y ago

As someone who is thinking about doing a python project, should I learn Django or just go with Flask? Any thoughts on those two?

dangoldin 13y ago
I think it really depends on what the project is. If it's relatively simple and you don't really want to deal with user registration/databases I'd say definitely go with Flask. Django does a pretty good job of those two but until it "clicks" you end up being confused.
- aartur 13y ago
  Funny that I wrote that Flask is for advanced usage and you wrote that Flask is for simple usage. If the project is really simple - no database, no declarative forms etc. - then Flask will be better. But if you go to "medium complexity" Django gives you ready components which you need to integrate in Flask (SQLAlchemy, WTForms etc.). You also need to invent your own project structure, and Django already has a hardcoded one. When the project complexity is "high" then Django starts to be too limited/"hardcoded" and flexibility/minimalism of Flask starts to shine.
  - dangoldin 13y ago
    Haha yea you're right! Funny how my bias trickled through. I haven't done too much Flask customization and only use it for the one off simple project that just need a web interface. Django is definitely more in the range of "we want you to write" this way but I've found it to be at least a bit more customizable than RoR. Flask is on the other extreme which lets you do whatever you want.. but you're the one who has to do it.
  - numlocked 13y ago
    I actually disagree. Flask does not necessarily shine with projects of high complexity. The framework designers themselves say as much: "However Flask is just not designed for large applications or asynchronous servers. Flask wants to make it quick and easy to write a traditional web application."[1] Flask is excellent when you just don't need a bunch of the stuff in Django, and don't need the batteries to be included. It's not so much that Flask is suitable to high-complexity apps, but more that it's suited to highly custom web apps. Building a music sharing app based on jQuery mobile and backed by Mongo? You're better off with Flask. But at scale you're going to end up doing something custom. Django is highly suitable if you need to manage users, have a variety of entities that lend themselves to the admin dashboard (more broadly, that the admin/public app metaphor even makes sense in the first place), and find a plug-and-play package system compelling. They are both great frameworks, but "complexity" (advanced/simple) is the wrong axis along which to evaluate them. [1]http://flask.pocoo.org/docs/design/ http://flask.pocoo.org/docs/design/
    - dvanduzer 13y ago
      The "large applications or asynchronous servers" bit might be better understood in comparison to the monolithic versus micro kernel debate. Flask is well suited for building complex applications that can be decomposed into simple moving parts with a clear separation of concerns. (My personal bias is that all complex applications can and should be developed this way.) The documented limitation you reference is based on the WSGI server being used. "If your server uses some kind of concurrency that is not based on threads or greenlets, Flask will no longer be able to support these global proxies."[0] As nginx+gunicorn is becoming more popular, this isn't really an issue at all. [0]http://flask.pocoo.org/docs/becomingbig/#scale-like-a-pro http://flask.pocoo.org/docs/becomingbig/#scale-like-a-pro
    - espeed 13y ago
      "However Flask is just not designed for large applications or asynchronous servers. Flask wants to make it quick and easy to write a traditional web application." Armin has said before that he needs to update/clarify that statement -- as dvanduzer said, it's not really relevant anymore.
ioddly 13y ago
I suppose it depends on what your goals are. If your goal is just to crank out some Python, I'd go with Flask (or my personal favorite Bottle).
aartur 13y ago
If you are new to Python and just want to have a working project instead of tinkering, then Django is better suited. Flask is for more advanced uses where you need to have more control or be able to integrate components you choose (like SQLAlchemy instead of Django ORM, or a NoSQL DB).
- mikeyouse 13y ago
  I disagree somewhat.. I'm a hobbyist at best when it comes to programming. Like I've never actually shipped anything in my life. I recently decided to put an end to that to solve a problem for a family member's business. They just wanted a simple web form, where the sales people could add notes throughout the day and then automatically email those notes to the owner at the end of the day. I first tried Django and was quickly overwhelmed.. I switched to Flask and with the help of flask-login, flask-wtforms, and flask-mail, it only took me a long weekend to get it up and running. Just a personal anecdote, but Flask was much easier for me.
  - obviouslygreen 13y ago
    Flask is definitely easier... it also offers far less. Which is fine in some circumstances -- perhaps many -- but the fact that Django has a steeper learning curve is due to the fact that it covers a lot more ground in terms of things many if not most web applications need. This doesn't make it better, but it also doesn't make it worse.
hamax 13y ago
I really like Flask but I still go with Django when I need the admin.
aidos 13y ago
Neither! Actually, as the others have said it completely depends on what you're making. Django is great if you're making a standard cms type website. News feed, blog, etc. There's a bit of a learning curve but it gives you a lot of the scaffolding out of the box (and there are loads of examples to learn from). It has the biggest community (I guess?) so you'll always be able to find answers / libraries / sample code. Use Flask if you really want to get a website up and running with half a dozen lines of code. You'll have to build everything else yourself; admin, authentication, etc etc - though there are good extensions for a lot of things too. Thinking about it - if you don't know either of them, spend a day with Flask, by the end of it you should have a fairly good idea of what you get with it. Then run through the Django tutorials. It'll take longer but you'll be impressed with how quickly you can get something fairly complete up and running. For me, I lean towards Flask (heavily). When you think about what Django does - it's basically a web container with a db/model layer and sensible scaffolding for the views (front and admin). I prefer to use SQLAlchemy (if I'm working with a relational db). In terms of the admin I think that the days of writing admin grid and edit screens that post back and forth to the server are numbered (I use REST and Angular now) - so that's not a bit of Django I use either. By the time you've ripped all that out you may as well save yourself all the config and just use Flask. Having said that - LEARN THEM BOTH. At least just a little bit so you can see for yourself where each one shines. These days I approach it completely differently. My last two projects have involved a fair amount of complex business logic (and processing work). I've written the libraries I needed first as standalone packages, only introducing Flask as a final step. The web wrapper is just there to provide a web interface (mostly an api) access the db layer and glue it all to my libraries. I'd recommend this approach as it stops you from thinking along the lines of "ok, I'll need to create 3 Django apps, here are my models for each, should I put this code in the models.py or the views.py?" Instead you concentrate on making the real python code to do the heavy lifting, and you architect that sensibly without having to worry about how the web framework would normally prescribe it to be done. You'll end up with far more portable code in the long run.
- mailshanx 13y ago
  What is your opinion about web2py? I started exploring it a week back, and it seems to have a lot of built in functionality. I thought it would be the easiest web framework to get started with (since it was originally built to help teach students about web programming). However, it seems to have a vast number of components, and it looks like learning all of it would entail almost the same effort as learning Django...
ConceitedCode 13y ago
You might also want to take a look at Pyramid. There's pros and cons for each.
- HarryRotha 13y ago
  I absolutely love pyramid, but I found the learning curve for it to be much higher than flask or django. If pyramid had a few more things working in a simple way out of the box I would go for it every time.
greghinch 13y ago
I've been building (more or less solo) a web app marketplace for our startup for about a year now. I love Python, and had dabbled in Django and Flask prior to this, but built nothing with either to any significant degree. I went with Django because I was able to get something up relatively quickly, and I feel like that was a solid decision. I also am relatively confident in my ability to move towards Flask in the longer term if the Django app becomes too much, but I haven't experienced that yet. Also Heroku has been mostly a godsend, as I haven't had to spend nearly any time on sysadmin stuff. One thing that caught me early on, not sure if it's a bug or what, but in Heroku, if you use git URLs for some of your packages in pip requirements (which is useful if you need to customize a package or more frequently fix a bug and can't wait for it to be pushed to pypi), Heroku's package cache has trouble knowing when to update unless you a) change the package version in its setup.py (may or may not be a good idea) or b) change the Python version in runtime.txt (kind of a pain as generally that means two deploys for an update, bump down one minor, then back up).
obviouslygreen 13y ago
Flask is so simple that it's definitely worth picking that up regardless (in any case, I think it's well done and worth having in your arsenal). However, for large web projects, Django beats it hands down. Doing similar work with Flask would require so much wheel-reinvention that it'd be hard to justify your time or your client's money when it's all built quite well already. Of course it's not perfect, and it's not for everything. But it's a great general-purpose, medium-performance web framework. It becomes a pain on very high-traffic sites (perhaps more so than JVM-based solutions and on par with scaling Ruby frameworks), but if you use it in the right place and/or team up with systems people that know their stuff, it's a powerful tool for quickly building complex websites in a maintainable and intuitive way.
- porker 13y ago
  Good point, I'd not thought about the JVM based Ruby solutions which can be used. If they'd give more Scala-like performance.. IronPython?

jspiral 13y ago

nice summary, sent to a colleague who is starting with django.

dangoldin 13y ago
Glad to have helped. If he/she has any questions you can have them reach out to me. I'm definitely not an expert but can offer some suggestions. dangoldin gmail is the email.

adamrt 13y ago

Using S3 for static media makes perfect sense, but does anyone have information on S3 when your contributors (users in the admin) are uploading lots of images for via something like django-filebrowser or a simple zipfile upload (that extracts the images into a folder)? I haven't seen anything like this in any examples.

stevenwei 13y ago
I think the standard method of dealing with this is to have your users upload the items to the local web server and then have some sort of async task or cron job responsible for moving the files to S3 later on. Of course this means you'll have to keep track of where the uploaded file is currently located, but if you ever want to scale to multiple web servers you'll need to do that anyway.
- dangoldin 13y ago
  Yea - this is how I've been doing it. The server that gets the upload does some processing and then moves the content over to S3 and adds an entry to the database that references it. It also forces you to write stateless code which is nice bonus.
obviouslygreen 13y ago
This is supported quite well via django-storages. Unless the libs you're using are doing something manual instead of using Django's built-in file handling, this will neatly override the local-filesystem defaults and send all of your content to S3. http://django-storages.readthedocs.org/en/latest/ http://django-storages.readthedocs.org/en/latest/
adrianh 13y ago
You can use S3's CORS support to allow your users to upload directly to S3 without even touching your server. Downside is that it can be hard to debug and it requires your users to use JavaScript -- but otherwise it's a big win. See http://philfreo.com/blog/how-to-allow-direct-file-uploads-from-javascript-to-amazon-s3-signed-by-python/ http://philfreo.com/blog/how-to-allow-direct-file-uploads-fr... for a Python example.

porter 13y ago

One more addition: Use heroku.

boffo9 13y ago
Heroku is the best!
porter 13y ago
Not sure why this got downvoted. I was being completely serious. Beat having to deal with fabric.

hiddentaco 13y ago

Great short and concise article. I'm in the process of writing a pet project using Django and would really appreciate your insights on what packages you find useful (as mentioned at the bottom of your post).

deleted 13y ago
[deleted]
obviouslygreen 13y ago
From someone who wasn't asked but has input... ;) It's not a Python package in the sense that you might mean, but using virtualenv is absolutely fundamental to good Python development (at least the kind that lets you keep your sanity). South is also exceptional; however, the developer recently ran a successful Kickstarter campaign dedicated to creating an improved version intended to be merged with Django itself, so that's something to watch for. Django-CMS has proven invaluable for many of my projects and clients, though it's very heavy and more of a project-tacked-on-to-your-project than just a package. It's great to know, though, and very powerful. django-registration can be useful if you're into full-on user profile usage, though many sites don't actually need this. There's a separate project that provides a set of default templates for this package, and it's almost more useful than django-registration itself. livesettings is an outgrowth of django-cms that's pretty useful when you need what would otherwise be settings.py constants that can be modified at runtime without a deployment and server restart. Be careful, though, as overuse of this means you might have design issues. feedparser is a very, very easy way to consume XML feeds. If you want to parse something in a very user-friendly way, BeautifulSoup is hard to beat. If you're into the nitty gritty and/or need serious performance, lxml serves the same purpose but kicks far more ass. If you need to interface with Amazon's AWS environments (EC2, S3, etc.), boto is a brilliant library. These are more Python-in-general than Django-specific, but that's often a good thing.
- hiddentaco 13y ago
  Thanks for the reply. While all suggestion are useful the biggest take away for me is livesettings. TBH I can't think of how I would use it at the moment but I can see that it could come in handy later.

tomkinstinch 13y ago

I'll add that if you need to background anything, django-celery makes it easy. celeryd is also good for scheduling tasks with either single or periodic execution. http://docs.celeryproject.org/en/latest/getting-started/first-steps-with-celery.html#first-steps http://docs.celeryproject.org/en/latest/getting-started/firs... You can also use it in a typical task queue role. It will pickle or serialize the Python objects that accompany tasks for transmission over the wire.

obviouslygreen 13y ago
Note that periodic execution, one of the more useful aspects of celery, is not supported on all backends. If you're using rabbitMQ, you're golden. If you're using most or all other transports (including SQS), you're likely SOL and will have to resort to either bare cron jobs or something like django-cronograph that accomplishes the same thing. celery is definitely nice, but it does have its limitations (like everything else).
- hiddentaco 13y ago
  I'm really interested in peoples opinion on Celery vs Others when using Django. I'm about to hit a point in my pet project where I need something but I havn't chosen my approach yet. I've ehard Pyres is better than Celery.
  - obviouslygreen 13y ago
    Once you wrap your head around one (embarrassingly, it took me a while to really understand what celery was doing -- I had an easier time getting comfortable with the multiprocessing library), it shouldn't be difficult to pick up another and compare them locally. Celery does what it's supposed to; that's about all I can say for it. I'd suggest writing a few simple jobs and testing them in similar environments under as much load as you can. Look for things like consistency of logging and running tasks exactly once across multiple consumers despite the semantics of the queue you pick.
- crdoconnor 13y ago

bluepanda_ 13y ago

Interesting post. I decided to use Django for our startup because Python was a requirement, we're planning to have a lot of customers, and Django seems like the most appropriate choice for large scale apps. While I've mostly used non-rel databases, I'll be using postgresql as a database, because it seems to be highly compatible with Django, because Heroku makes scaling it easy, and because it's a good occasion to learn some RDBMS.

boffo9 13y ago

I'll add that you should read Two Scoops of Django at http://django.2scoops.org http://django.2scoops.org

porker 13y ago

How well does Django handle complex forms? The kind where "if x = y show fields p-r (and make them required), if x = z jump the next screen)? I've just implemented one of these in PHP using the 'old' Symfony 1.4 and it was painful. I ended up hardcoding most of the frontend, and writing ridiculous modifications for "add another row" and validation. Is Django any better at that? Complex forms have been my pain point for over 11 years, and if a framework handles them... I'm in!

ShaunCodeweaver 13y ago
Very much this - though I've experienced this in other stacks. Would love to know the best way people handle this.
scott_w 13y ago
If I'm understanding you correctly, you want to have the fields on the form depend on the contents of what was entered on the previous form e.g. if user selects name, ask for name, otherwise ask for address. In that case, I tend to use class-based views and set different forms, templates etc. depending on those values. If the form is different enough, it's easier just to send them to a completely different URL.
- porker 13y ago
  Not quite - that happens sometimes and I use logic in the controller (ugh) to switch the form class. This is what I mean: an adaptive form http://screencast.com/t/SutggDU5 http://screencast.com/t/SutggDU5 The server-side validation has to adapt depending on the data coming from the client-side, and varies a lot. Perhaps others don't build forms like this much and so web frameworks don't deal with them; I get one like this every few months!
  - scott_w 13y ago
    Ah, I see now. For certain cases e.g. repeating the same form over and over, you can use formsets, but that doesn't work when you have two different forms. I still think a solution is to use multiple forms and form types rather than one big form. Perhaps you can prefix the field names on the template and use that to determine which form they go to inside the view. It makes your logic a little simpler in any case.

groundCode 13y ago

Nice post thanks - I'm about to tackle a fairly large Django project so it's always nice to see some best practice guidelines

scott_w 13y ago

For dealing with packages such as python-psycopg2 and python-mysql, your best bet is to use --system-site-packages. This allows the virtualenv to depend on packages provided by your distro instead of trying to compile its own. Wherever possible, I try to do this with Python packages that require a C compiler to make deployment a little easier and reduce dependencies. Personally, I'm not a fan of Fabric and I much prefer configuration management (Salt, Chef, Puppet) because of the added flexibility you get. About the most I use Fabric for is logging into the Salt Master and kicking off a deployment process.

antihero 13y ago
Absolutely not. An added bit of compile time is the least of your worries and if you really don't want to compile stuff on production, look at packaging your virtualenv as a compiled deb/rpm. Never ever ever mix/depend upon system packages in your virtualenv. Ever.
- scott_w 13y ago
  You're always depending on system packages somewhere. Compiling isn't the only reason - sometimes it's necessary just to make the damn thing work. Some examples: * PIL - Using Pip's version on Ubuntu, you have to hack your directory structure and re-compile the whole thing or PIL doesn't compile in support for your image libraries. * psycopg2 - This is hit and miss (OS X comes to mind), but depending on the system version guarantees that it has been tested to work with the specific version of Postgres on your system. * Crypto libraries - Broken packages have ended up on Pip and just cause a bloody headache. The system package is, again, tested and works. Compiling a DEB/RPM would be a good idea, but it's not a well supported system at all. If there were a simple pip compile --type=deb or something, we would be all over it.
  - antihero 13y ago
    PIL - Don't use PIL, use Pillow. Psycopg2 - Well, it's just a client library - surely you will be making sure your client matches your server's version (whether that's local or a clust or whatever)? Sure your system will likely need Postgres headers installed, but why is that an issue? Actually, let me just check that. e: Yeah, you need libpq-dev installed, but I fail to see the point here? You need to make sure you have python-dev and a correct version of Python installed, too. PyCrypto - Hmm, not had a problem with this hugely. What I was suggesting doesn't involve a deb of individual packages, but a deb of the entire app/virtualenv.

jordn 13y ago

For those who would like to get started with Django, here's a skeleton project https://github.com/jordn/heroku-django-s3 https://github.com/jordn/heroku-django-s3 and guide helps get you set up quickly with: - hosting on heroku - static files on Amazon S3 - virtualenv(wrapper) isolated packages - environment and security critical variables removed from settings.py and stored as environment variables (following the 12-factor design ethic)

iends 13y ago
I have a couple of thoughts: 1. Why not use django-admin.py startproject --template=<url>? I typically do something like django-admin.py startproject --template=https://github.com/rdegges/django-skel/zipball/master https://github.com/rdegges/django-skel/zipball/master mynewproject so I don't actually have to clone 2. No runtime.txt for heroku? 3. Not specifying version numbers in your requirements.txt is very dangerous. I prefer something like "Django>=1.5.0,<=1.5.9"
- jordn 13y ago
  Thanks! Basically the answer is that I wasn't aware of the possibility of those things and have tried to keep it as simple as possible. I made a skeleton project for me as I couldn't find a decent guide for deploying django static's on s3. I fumbled my way through it and corrected and formalised it later so I could do it again. The https://github.com/rdegges/django-skel https://github.com/rdegges/django-skel project looks really useful as it contains everything and more you might want to use for a django project (and more), though not yet knowing what magic's it's doing I wouldn't yet jump to use. 1. That is very neat. I hope to try and copy that. 2. Noted. I didn't realise the need, as python 2.7.4 is the default. Can see it causing headaches if this were to change however. 3. Why is it dangerous? I preferred to keep the version numbers so it would always just install latest versions without any extra effort.
  - iends 13y ago
    The reason it's dangerous is that packages can introduce backwards incompatible changes. If you have a project that you don't work on for a few weeks/months and then need to fix a bug, you're going to have to spend additional cycles tracking down the issue and fixing either the backwards incompatible change, or adding a specific version to your requirements file anyway. I like to try and scope the package versions at the level the maintainer promises not to introduce breakages at.

ludwigvan 13y ago

Here are a few other Django packages that I haven't seen mentioned in this thread: - Gargoyle: Feature switches in Django https://github.com/disqus/gargoyle https://github.com/disqus/gargoyle - webassets and django-assets: For minifying static assets - raven + sentry for logging. Sentry is the server, so actually can be used with any project, not only Django. - django_extensions: Provides some helper management commands, for example manage.py shell_plus which automatically imports your models - dbbackup for backing up your db to S3 or Dropbox